Tires

ABSTRACT

A pneumatic tire having tread or subtread incorporating lengths of steel wires substantially shorter than thread width distributed throughout the depth and circumference of the tread, subtread or both, each wire having a diameter of substantially 0.003 of an inch or less.

United States Patent Henry R. Fletcher, deceased late of Ward End,Birmingham, England; Agnes Marion Fletcher, legal representative, 219,Coleshill Road, Ward End, Birmingham 34, Warwickshire,

[72] Inventors England [21] Appl. No. 834,614 [22] Filed June 17, 1969[45] Patented Oct. 5, 1971 [32] Priority June 22, 1968 [3 3] GreatBritain [31] 29880/68 [54] TIRES 2 Claims, 1 Drawing Fig.

[52] U.S.Cl

[51] lnt.Cl B60c 9/16 [50] Field of Search 152/210, 211, 212

[56] References Cited UNITED STATES PATENTS 2,910,104 10/1959Billingsley 152/211 3,057,389 10/1962 Dubetz et al 152/210 PrimaryExaminer-James B. Marbert Attorney-Stevens, Davis, Miller & MosherABSTRACT: A pneumatic tire having tread or subtread incorporatinglengths of steel wires substantially shorter than thread widthdistributed throughout the depth and circumference of the tread,subtread or both, each wire having a diameter of substantially 0.003 ofan inch or less.

TIRES This invention relates to pneumatic tires.

Pneumatic tires hitherto known having a damage-resistant tread orsubtread for use on earthmover and off-theqoad truck tires generallycomprise a limited weight of small lengths of steel filaments, of atleast 0.0059 inches diameter disposed in said tread or subtread.However, such constructions suffer from lack of homogeneity andconsequently a tendency of the tread to tear, split or chunk exists.

It is an object of the present invention to reduce or substantiallyeliminate the aforesaid difficulties.

According to the present invention there is provided a pneumatic tirehaving a tread or subtread incorporating lengths of steel wiressubstantially shorter than the tread width distributed throughout thedepth and circumference of the tread or subtread or both, each wirehaving a diameter of substantially 0.003 of an inch or less.

Said lengths may be nonorientated.

Alternatively said lengths are orientated in any specific direction e.g.circumferentially.

One embodiment of the invention will now be described in more detail byway of example with reference to the accompanying drawing which shows adiagrammatic fragmentary axial cross'sectional view of a pneumatic tireaccording to the embodiment.

An earthmover tire comprises a radial ply carcass reinforcement 4 and abreaker assembly 3. The tread composition 1 comprises a polyisoprenerubber composition of approximately 73 Shore hardness to which aplurality of steel filaments each of length between 9% and 3 inches andof diameter approximately 0.003 inches has been added and intimatelymixed, to achieve a random distribution and orientation of steelfilaments within said base. Said random distribution and orientationexists circumferentially axially and radially. The subtread 2 of thetire is devoid of steel filament reinforcement.

A tire constructed according to the invention has many advantages. Theuse of fine wire as compared with coarser wire hitherto used permits amuch greater number of individual filaments to be used for the sameweight and consequently homogeneity of the tread compound is improved,producing a tire of more uniform performance. In addition said greaternumber of filaments has a substantially greater surface area and thusbonding between the tread or subtread composition and said filaments issubstantially improved.

General handling and processing of the filaments, tread compositions andthe tire is also improved due to increased flexibility of the wires,ease of cutting the wires and mixing of the tread composition.

Having now described my invention what I claim is:

l. A pneumatic tire having tread or subtread incorporating lengths ofsteel wires substantially shorter than tread width distributed randomlythroughout the depth and circumference of the tread, subtread or both,each wire having a diameter of substantially 0.003 of an inch or less.

2. A pnuematic tire according to claim 1 wherein the length of each ofthe said lengths is between hand 3inches.

1. A pneumatic tire having tread or subtread incorporating lengths ofsteel wires substantially shorter than tread width distributed randomlythroughout the depth and circumference of the tread, subtread or both,each wire having a diameter of substantially 0.003 of an inch or less.2. A pnuematic tire according to claim 1 wherein the length of each ofthe said lengths is between 1/2 and 3inches.